A typical brushless motor of the IPM (Internal Permanent Magnet) type, comprises a stator and a rotor rotatably mounted to the stator. The stator comprises a stator core and stator windings wound about teeth of the stator core. The rotor comprises a rotor shaft, a rotor core fixed onto the rotor shaft and permanent magnets inserted into slots in the rotor core.
Magnetic leakage is a problem for an IPM brushless motor since the permanent magnets are embedded in a magnetically conductive rotor core. Furthermore, the stator core has a risk of magnetic saturation which would make it difficult to control the motor.
Hence there is desirable for an improved brushless motor of the IPM type.